Ion-exchange processes are employed to vary and control the concentration of metal ions in various glass, glass-ceramic and ceramic substrates through localized compositional modifications. These compositional modifications in the substrates can be used to modify certain substrate properties. For example, alkali metal ions (e.g., Na and K ions) may be imparted into surface regions of substrates as a strengthening mechanism. As another example, various heavy metal ions (e.g., Ag, Cu and Zn ions) can be imparted into surface regions of substrates to provide the substrate with anti-microbial properties.
These ion-exchange processes often involve the immersion of substrates in a molten salt bath at elevated temperatures. The molten salt bath includes metal ions intended to be introduced into the substrates. Ions in the substrates are exchanged with the metal ions in the bath during the ion-exchange processes. Various ions are desirable for use in ion-exchange processes; however, many commercially available salts have high melting points far above ambient temperatures. The high melting points of these salts often exceed the stress point of the intended glass, ceramic, or glass-ceramic and cannot be used. In addition, molten salts often have high viscosities, an issue which can negatively influence the kinetics of ion-exchange processes using molten salts.
Accordingly, there is a need to develop systems and methods suitable for manufacturing operations that can be used to produce strengthened and antimicrobial glass, glass-ceramic, and ceramic articles.